Introduction

Sass, Less, and SCSS code is not processed by browsers that work with CSS code. Therefore to be executed, Sass, Less, or SCSS code has to be translated into CSS. This operation is referred to as compilation and the tools that perform it are called compilers.

IntelliJ IDEA integrates with compilers that translate Sass, Less, and SCSS code into CSS. To use integration in IntelliJ IDEA, you need to configure compiler as a File Watcher. For each supported compiler, IntelliJ IDEA provides a predefined File Watcher template. Predefined File Watcher templates are available at the IntelliJ IDEA level. To run a compiler in a project, create a project-specific File Watcher based on the relevant template.

Before you start

Make sure the Less Support, Sass Support, and CSS Support plugins are activated. The plugins are activated by default. If the plugins are disabled, enable them on the Plugins page as described in Enabling and Disabling Plugins.

Installing the Sass/SCSS compiler

Specify a path variable for the folder where the Ruby executable file and the gem.bat file are stored. This lets you launch Ruby and Gem Manager from any folder and ensures that Ruby is successfully launched during compilation.

Type the following command at the command prompt:

geminstallsass

The tool is installed to the folder where Ruby executable file and the gem.bat file are stored.

Installing the Less compiler

The easiest way to install the Less compiler is to use the Node Package Manager (npm), which is a part of Node.js. See NPM for details.

Depending on the desired location of the Less compiler executable file, choose one of the following methods:

Install the compiler globally at the IntelliJ IDEA level so it can be used in any IntelliJ IDEA project.

Install the compiler in a specific project and thus restrict its use to this project.

In either installation mode, make sure that the parent folder of the Less compiler is added to the PATH variable. This enables you to launch the compiler from any folder.

IntelliJ IDEA provides user interface both for global and project installation as well as supports installation through the command line.

Installing the Less compiler globally

Global installation makes a compiler available at the IntelliJ IDEA level so it can be used in any IntelliJ IDEA project. Moreover, during installation the parent folder of the compiler is automatically added to the PATH variable, which enables you to launch the compiler from any folder.

Run the installation from the command line in the global mode:

Open the embedded Terminal (View | Tool Windows | Terminal) and switch to the directory where NPM is stored or define a PATH variable for it so it is available from any folder, see Installing NodeJs.

Type the following command at the command prompt:

npm install -g less

The -g key makes the compiler run in the global mode. Because the installation is performed through NPM, the Less compiler is installed in the npm folder. Make sure this parent folder is added to the PATH variable. This enables you to launch the compiler from any folder.

Run NPM from IntelliJ IDEA using the Node.js and NPM page of the Settings dialog box.

Open the Settings / Preferences Dialog by pressing Ctrl+Alt+S or by choosing File | Settings for Windows and Linux or IntelliJ IDEA | Preferences for macOS, and click Node.js and NPM under Languages & Frameworks.

On the Node.js and NPM page that opens, the Packages area shows all the Node.js-dependent packages that are currently installed on your computer, both at the global and at the project level. Click .

In the Available Packages dialog box that opens, select the required package to install.

Select the Options checkbox and type -g in the text box next to it.

Optionally specify the product version and click Install Package to start installation.

Installing the Less compiler in a project

Local installation in a specific project restricts the use of a compiler to this project.

Run NPM from IntelliJ IDEA using the Node.js and NPM page of the Settings dialog box.

Open the Settings / Preferences Dialog by pressing Ctrl+Alt+S or by choosing File | Settings for Windows and Linux or IntelliJ IDEA | Preferences for macOS, and click Node.js and NPM under Languages & Frameworks.

On the Node.js and NPM page that opens, the Packages area shows all the Node.js-dependent packages that are currently installed on your computer, both at the global and at the project level. Click .

In the Available Packages dialog box that opens, select the required package.

Optionally specify the product version and click Install Package to start installation.

Project level installation is helpful and reliable in template-based projects of the type Node Boilerplate or Node.js Express, which already have the node_modules folder. The latter is important because NPM installs the Less compiler in a node_modules folder. If your project already contains such folder, the Less compiler is installed there.

Projects of other types or empty projects may not have a node_modules folder. In this case npm goes upwards in the folder tree and installs the Less compiler in the first detected node_modules folder. Keep in mind that this detected node_modules folder may be outside your current project root.

Finally, if no node_modules folder is detected in the folder tree either, the folder is created right under the current project root and the Less compiler is installed there.

In either case, make sure that the parent folder of the Less compiler is added to the PATH variable. This enables you to launch the compiler from any folder.

Creating a file watcher

IntelliJ IDEA provides a common procedure and user interface for creating File Watchers of all types. The only difference is in the predefined templates you choose in each case.

To start creating a File Watcher, open the Settings/Preferences dialog box by choosing File | Settings for Windows and Linux or IntelliJ IDEA | Preferences for macOS on the main menu, and then click File Watchers under the Tools node. The File Watchers page that opens, shows the list of File Watchers that are already configured in the project.

Click the Add button or press Alt+Insert. Depending on the tool you are going to use, choose the appropriate predefined template from the pop-up list:

Less

Sass

SCSS

In the Program text box, specify the path to the compiler executable file or archive depending on the chosen predefined template.

lessc.cmd for Less If you installed the tool through the Node Package Manager, IntelliJ IDEA locates the required file itself at <node.js_home>/node_modules/bin/lessc.cmd and fills in the field automatically. Otherwise, type the path manually or click the Browse button and choose the file location in the dialog box that opens.

sass.bat for Sass

scss.bat for SCSS

If you installed the Sass and SCSS tools through Ruby, IntelliJ IDEA locates the required files itself at <ruby_home>/bin/sass.bat<ruby_home>/bin/scss.bat respectively and fills in the field automatically. Otherwise, type the path manually or click the Browse button and choose the file location in the dialog box that opens.

Compiling the code

When you open a Less, Sass, or SCSS file, IntelliJ IDEA checks whether an applicable file watcher is available in the current project. If such file watcher is configured but disabled, IntelliJ IDEA displays a pop-up window that informs you about the configured file watcher and suggests to enable it.

If an applicable file watcher is configured and enabled in the current project, IntelliJ IDEA starts it automatically upon the event specified in the New Watcher dialog.

If the Immediate file synchronization check box is selected, the File Watcher is invoked as soon as any changes are made to the source code.

If the Immediate file synchronization check box is cleared, the File Watcher is started upon save (File | Save All, Ctrl+S) or when you move focus from IntelliJ IDEA (upon frame deactivation).

IntelliJ IDEA creates a separate file with the generated output. The file has the name of the source Sass, Less, or SCSS file and the extension css. The location of the generated files is defined in the Output paths to refresh text box of the New Watcher dialog. However, in the Project Tree, they are shown under the source file which is now displayed as a node.